In this paper, a cathode-plasma electrolysis setup with atmospheric pressure pin-to-solution electrical discharge in air and AgNO3 aqueous solution is used. The experiment shows that a black powder is generated at the plasma-solution interface. Through x-ray diffraction (XRD), energy dispersive x-ray spectrometry (EDS) and Fourier-transform infrared (FTIR), the black powder is found to be Ag2O2 combined with a small amount of Ag2CO3. Field-emission scanning electron microscope (FESEM) images reveal that the powder is a mixture of sub-micrometer (>200 nm) Ag2O2 polygonal particles and Ag2CO3 nano-spheres of < 70 nm diameter.
